MXPA00005159A - Improved electrochemical biosensor test strip - Google Patents

Abstract

The biosensor includes a first insulating substrate (1), with a first surface (22) and a second surface (23). The substrate (1) further includes indentation (2), notch (3) and vent hole (4).

Description

IMPROVED ELECTROCHEMICAL BIOSENSOR TEST STRIP FIELD OF THE INVENTION This invention relates to a biosensor and its use in the detection or measurement of fluid analyzes.

BACKGROUND OF THE INVENTION The prior art includes the test strips, which include the electrochemical test biosensing strips, for measuring the amount of the analyzes in a fluid. The particular use of such test strips has been made to measure the glucose in human blood. Such test strips have been used by diabetics and health care professionals to monitor their blood glucose levels. The test strips are usually used in conjunction with a meter, which measures the reflectance of the light, if the test is designed for the photometric detection of a hue, which measures some electrical property, such as the electrical current, if the Strip is designed for the detection of an electrically active compound. However, the test strips that have been previously made present certain problems for the individuals who use them. For example, the test strips are relatively small and a deteriorated diabetic view may have difficulty in appropriately adding a blood sample to the sample application area of the test strip. It would be useful for the test strip to be made so that people with impaired eyesight could easily dose the test strip. When the test strip is a full capillary device, that is, when the chemical reaction chamber of the test strip is a capillary space, particular problems may occur - with the filling of the chamber uniformly and sufficiently with the liquid sample to be tested Due to the smallness of the capillary space and the composition of the materials used to make the test strip, the test sample may waver upon entering the capillary reaction chamber. Additionally, insufficient sample may also be wasted within the capillary reaction chamber, thereby resulting in an inaccurate test result. It would be very useful if such problems could be minimized. Finally, test strips, especially those used by diabetics to measure glucose in the blood, are mass produced. Processes, such as mechanical perforation, used to make these test strips, can cause a test reagent that has dried on a surface of the test area to crack or break, causing such a moa; loss of reagent or improper placement of the reagent within the strip. It would also be useful to design a test reagent that could withstand the steps of the process, such as mechanical drilling. The electrochemical biosensing test strip of the present invention provides solutions to these raised problems encountered in the prior art of the test strips.

SUMMARY OF THE INVENTION The invention is an improved electrochemical biosensing test strip with four highly advantageous new features. The first characteristic is a slit along one edge of the test strip for easy identification of the port of application of the sample for people with impaired sight or for use in conditions of zero or low luminosity. The test strip has a test capillary, and the camera cover includes the second new feature of the biosensor test strip. The second new feature is a transparent or translucent window which operates as a fill-up line, identifying such mod when sufficient test sample (a liquid sample, such as blood) has been added to the test chamber to run with precision a test. The window defines the minimum amount of sample, or dose, required to run a test safely, and, therefore, represents a visual salvo and which reduces the chances of erroneous test results due to the underdosing of a test strip. The length and width of the window are shorter than the wide length of the test capillary. The window is dimensioned and positioned so as to cover the total width of the electrode in operation and at least about 10% of the width of the counter or reference electrode of the biosensor test strip. Preferably, the area of the cover that surrounds the window is colored in a way that provides good color contrast between the sample, while looking through the window, and the area of the cover that surrounds the window for the facilitated identification of Sufficient dosing of the strip. The third new feature of the test strip is the inclusion of a notch, or multiple notches, located at the sample application port. A notch is created in the first insulating substrate and in the cover of the strip. These notches are dimensioned and positioned such that they cover each other on the test strip. These notches reduce a phenomenon called dose hesitation. When a ß sample is added to the strip sample application port without notch, the sample may waver at its input into the capillary test chamber. This hesitation of dose adds to the time d test. When the test strip includes a notch, the dose titube is reduced. Additionally, including the notch in the first insulating substrate and cover makes it possible for the test sample to approach the test application port from a wide variety of angles. The approach angle for the test sample would be more limited if the sample were only on the cover. Finally, the fourth new feature of the test strip is a reagent that includes polyethylene oxide from about 100 kilodaltons to about 90 kilodaltons, which means molecular weight in concentration from about 0.2% (weight: weight) to about of 2 (weight: weight), which makes the dry reagent more hydrophilic firm. With the inclusion of polyethylene oxide, the test reagent can more easily resist mechanical perforation during strip assembly and mechanical manipulation by the user of the test strip. Additionally, the dry reactiv, which will include from about 1.75% (weight to about 17.5% (weight: weight) polyethylene oxide can be easily redissolved, or resuspended, when an aqueous test sample is added to the test chamber of the strip.

Brief description of the illustrations Fig. 1 is a schematic view of a preferred embodiment of the present invention. Fig. 2 shows a preferred fully assembled test strip. Figs. 3a-3i represent a preferred method of making the test strip of the inventive. Fig. 4 is a cross-sectional view of the test strip of Fig. 2 through line 28-28. Fig. 5 is a cross-sectional view of the test strip of Fig. 2 through line 29-29. Fig. 6 illustrates the hypothetical calibration curves for different batches of test strips.

DESCRIPTION OF THE INVENTION The components of a preferred embodiment of the present inventive biosensor are shown in Figures 1, 2, 4 and 5. The biosensor includes the first insulating substrate 1, which has the first surface 22_ and the second surface 2_3. The insulating substrate 1_ can be made of any useful insulating material. Typically, plastics, such as vinyl polymers, polyimides, polyesters, and styrenes, provide the electrical and structural properties, which are desired.

The first insulating substrate JL additionally includes slit 2 / notch 3, and a vent 4. Because the biosensor shown in Fig. 1 is intended to be mass produced from rolls of material, necessitating the selection of a material which is sufficiently flexible for the coiling process and at the same time sufficiently rigid to give a useful tension to the finished biosensor, a particularly well-presented JL insulation substrate is the plastic MELINEX 329 of 7 mil thickness, a polyester available from ICI Films (3411 Silverside Road, PO Box 15391 Wilmington, Delaware 19850). As shown in Fig. 1, electrically conductive tracks 5 and 6 are supported on the first surface 2 of the first insulating substrate .1. Track 5 must be an electrode in operation, made of electrically conductive materials such as palladium, platinum, gold, carbon, titanium. Track 6 should be a counter electrode, made of electrically conductive materials such as palladium platinum, gold, silver, silver containing alloys, nickel-chromium alloy, carbon, titanium, and copper. Noble metals are preferred because they provide a surface for the reproducible electrode, more constantly. Particularly preferred palladium is one of the noble metals with greater difficulty in oxidizing and because it is a relatively inexpensive metal. Preferably, the electrically conductive tracks 5 and are deposited on an insulating support, such as polyester polymers, to reduce the possibility of tearing the electrode material during the handling and manufacture of the test strip. An example of such conductive tracks is a palladium cube with a surface resistance of less than 5 ohms per square inch on the UPILEX polyimide support, available from Courtalds-Andus Performance Films in Canoga Park, California.

The electrically conductive tracks 5 and 6 represent the electrodes of the biosensor test strip. These electrodes must be sufficiently separated in such a way that the electrochemical events in one electrode do not interfere with the electrochemical events in the other electrode. The preferred distance between electrodes 5 and 6 is about 1. millimeters (mm). In the test strip shown in Fig. 1, the electrically conductive piston would be the electrode in operation, and the electrically conductive track 6 would be a reference electrode counter electrode. Track 6 would be a reference electrode if it is made of typical electrode reference materials, such as silver / silver chloride. In a presented embodiment, track 5 is an electrode in operation made of palladium, and track 6 is a counter electrode which is also made of palladium and is substantially of my size as the electrode in operation. Three arrays of electrodes are also possible, in which the strip includes an additional electrically conductive track located between the conductive track 6 and vent 4. In a three-electrode array, the conductive piston 5 would be an electrode in operation, track 6 would be a counter electrode, and the third electrode between track 6 the vent 4 would be a reference electrode. The second insulating substrate 7. is overlapping the conductive tracks 5 and 6. The. second insulating substrate 7 is made of a similar material, or the same preferably, as the first insulating substrate 1. The substrate JL has a first surface 8 and a second surface 9. The second surface 9 is fixed to the surface of the substrate 1 and the conductive tracks 5 and 6, by an adhesive, such as a hot melt pegament. An example of such glue is glue DYNAPOL S-1358, available from. Hüls America Inc. Davidson Street, PO Box. 6821, So erset, NJ 08873. The substrate JL also includes the first opening O and the second opening 11. The first opening JJ exposes portions of the conductor tracks 5 and 6 for the electrical connection with a meter, which measures some electrical properties of a test sample after the test sample mixed with the reagent of the test strip. The second opening XX exposes a different portion of the conductive pistons 5 and £ for the application of the test reagent to those exposed surfaces of the tracks 5 and 6. (In Fig. 1, the entire width of the conductive tracks 5 and 6 exposed through the opening XX However, it is also possible to expose only a portion of the width of the conductive track 6, which is either one of the counter electrodes or reference electrodes, as long as at least about 10% of the width , is exposed by the opening 11) Additionally, the second insulating substrate 2 includes slit 19, which coincides with the slit 2 as shown in Fig. 1. The test reagent 12 is a reagent that is specific for the test to be executed by the test strip. XZ reagent can be applied to the entire surface area of the conductor tracks 5 and 6 in the area defined by the second aperture 11. Other applications of the reagent. they are also possible in this region. For example, if the conductive pee 6 in this region of the strip has a reference electrode construction, such as silver chloride / plat then the test reagent JL2 may need only cover the exposed area of an electrode 5 in operation in this region. Regió II Additionally, the entire exposed area of an electrode may not need to be covered with test reagent as well as a well-defined, reproducible area of the electrode is covered with the reagent. Covering a portion of a first surface 8 and a second opening XX is the cover .13. The cover 13 includes the slit 14 and the notch J5. The slit JL4 and the notch are formed and positioned so as to directly cover the slits and 2JH, and the notch 3 ^. The cover 43 can be made of a plastic material, such as a transparent or translucent polyester foil of thickness from about 2 mils to about 6 ilipulgadas. The cover 13 has a first surface 16 and a second surface 1 The second surface XI of the cover JL3 is fixed to the first surface 8 of the second substrate JL by a suitable adhesive, such as the acrylic 3M 9458, available from 3 Identification and Converter Systems Division, 3M Cente Building 220-7W-03, St. Paul, MN 55144. Preferably, the cover 13 additionally includes transparent or translucent JL8 window. The window 18 dimensioned and positioned in such a way that when the cover. is fixed to the second insulating substrate T_, the window covers the entire width of the conductor track 5 and at least about ten percent of the width of the conductor track 6.

The second surface 17. of the cover, 13, the edges of the opening XX, and the first surface ZZ of the insulating substrate X (and the conductive tracks 5 and jS fixed to the first surface ZZ of the substrate JL) define a test capillary chamber. The length and width of this capillary chamber is defined by the length and width of the opening XX and the height of the chamber is defined by the thickness of the second insulating substrate JL. A test strip presented can be manufactured as shown by the process illustrated by Figs. 3a-3i. U material sheet of the insulating substrate 21 (MELINEX 329, milled in thickness, available from ICI) is coated on one side with the melted adhesive (DYNAPOL S-135 available from Hüls). (Fig. 3a) the sheet 21 is cut along the line 4, in such a way that it forms the first insulating substrate 1, coated with the adhesive on the first substrate 22, and the second insulating substrate 7, coated with adhesive on the second substrate 9. (Figs 3b and 3c). The first opening 10 and the second opening XX are created in substrate JL by die-cutting (Fig. 3d). Then, the electrically conductive tracks 5 and 6, made of paddle on an Upilex support (available from the Courtalds-Andus film execution), are unwound from pre-cut reels about 1.5 millimeters wide and supported on the ZZ surface of the substrate 1 in such a way that the Upilex support is adjacent to the surface ZZ - The surface 9 d of the substrate 7 is supported adjacent to the surface of the substrate 1 and to the conductor tracks 5 and 6, so that they form the sandwich structure shown in FIG. 3e. This sandwich structure is heat sealed. A test reagent 12 is then distributed into the opening XX and dried (Fig. 3f). After the reagent 12 is dry, the vent 4 is created by a perforating die (Fig. 3g). Then, the cover ü, which includes hydrophilic coating 25 and the window 8 is supported above the opening H such that the window 18 covers the entire width of the conductive track 5 and about u half the width of the conductive track 6. The cover 13 releases a release liner and is fixed in adhesive manner to the surface 8 as shown in Fig. 3h. Finally, individual test strips are punched in a punching hole as shown in Fig. 3i. Die punching can puncture the test strips with the notch 15. If the notch 15 is included, the preferred angle of the apex is 105 °. Other angles, such as from about 45 ° to about 105 °, are also possible for the notch.15. Additionally, the notch 15 can be a single notch or multiple notches.

As noted above, the test reagent 12 e is distributed within the area of the test strip defined by section XX. In the manufacturing process described above, it is preferred to provide the corona H opening treatment before the test reagent 12 is applied. The application of the corona treatment serves to increase the surface energy of the surface portion ZZ and the conductive tracks 5 and 6 exposed by the opening ü, generating the uniform propagation of the reagent 12, and to pre-li the portion of the conductor tracks 5 and 6 exposed by the opening XX. The pre-cleaning of the conductor tracks 5 and 6 s has been found to significantly improve the performance of the test strip. The corona treatment can be applied Watt densities placed from around 20 hast around 90 watts per centimeter per second (W / cm / s) with a gap arc of about 1 millimeter (0.040 inches). In the presented method, the corona treatment is applied from the surfaces shown in Fig. 3e to the Watt densities described above, the treatment is more effective if applied within 5 minutes of the application of reagent 12 and It is typically practical within 45 seconds of the application of reagent 12. It is advantageous to reduce the effects of the coronary treatment on the surface 8 to ensure that the reagent 12 s completely combines in the opening H and has no affinity for the surface 8 that by the portion of the surface 22 and the conductive tracks 5 and ü exposed by the opening 11 A corona dissipation process, which allows the selective reduction of the effects of a layer of the corona treatment process, is incorporated to reduce the effects of treatment in the areas of the membrane (the sheet of test strips that are processed) outside the opening 11. This corona dissipation process involves applying a film Thin deionized water such that the water contacts the surface 8, but will not contact the openings 10 and 11. The application of the thin film of water, which preferably ranges from about 1.5 microns to about 3.0 microns in thickness (about of 9.1 grams of water per square meter), can be made via flexographic printing printing bearing, or other commercial coating application method available. The thin film of water is then dried from the surface, using forced convection or infrared methods only before the application of reagent. The net effect of this treatment is that the surface energy of the surface 8 is effectively reduced to less than 62. dinas before the application of the reagent 12 while the surface area within the opening XX is maintained at its surface energy before corona treatment. In the embodiment presented, the test reagent 12 is formulated for the measurement of glucose in a human blood sample. A protocol for the preparation of a liter of a presented glucose reagent, which uses the enzyme quinoprotein (which contains quinone pyrrolo-quinoline (PQQ)) glucose dehydrogenase and the redox mediator of ferricyanide shows immediately below (the quinoprotein glucos dehydrogenase is the Enzyme Commission No. 1.1.99.17). Step 1: Prepare a NATROSOL solution in deionized water. This is done by adding 0.45 grams (g) of NATROSOL-250M (available Aqualon microcrystalline hydroxyethylcellulose) to 414g of deionized water while mixing at a speed of not less than 250 revolutions per minute (rpm for a period of not less than 30 minutes , the mix is best performed with a superheated rotating impeller that uses a three or four blade turbine propeller.The selection of propeller size and configuration are mostly based on the radius of the mixing vessel used. will typically have a radius greater than 75% radius of the mixing vessel Step 2: To the solution of Step 1, 5.6g .d AVICEL RC-591F (a microcrystalline cellulose available from FM Co.) is dispersed gradually, adding this AVICEL to the solution while mixing at a speed of not less than 570 r.p.m. for less than 60 minutes. Step 3: To the mixture of Step 2, 8.4 of polyethylene oxide (which means a molecular weight of 30 kilodaltons) are gradually added, while mixing at a speed of not less than 690 r.p.m. for a period of not less than 45 minutes. Step 4: A buffer solution is prepared by adding 12. lg of potassium phosphate monobasic (anhydrous) and 21.3g d potassium phosphate dibasic (anhydrous) to 450g. de de deionizada. Step 5: A 50g aliquot of the buffer solution removed for the preparation of Step 4. At this 50g aliquot, 12.5 mg of PQQ coenzyme (available from Fluka) is added. This solution is mixed until the coenzyme is completely dissolved (a magnetic mixing bar and its magnetic mixing plate are preferred for the preparation of the enzyme). Step 6: To the solution of Step 5, 1.21 million units of the protein quino protein dehydrogenase apoenzyme are added gradually while mixing at low speed (less than 400 rpm in a magnetic mixing dish) to prevent frothing . The resulting solution is mixed for not less than 2 hours to allow the association of the enzyme and the coenzyme to stabilize, resulting in a glucose dehydrogenase quinoprotein solution. Step 7: To the buffer solution of Step 4, add 59. lg of potassium ferricyanide. Then, 6.2 g of sodium succinate is added. The solution that results is. Mix until all solutions are completely dissolved. After the dissolution. The pH of the solution is estimated and is required to be approximately 6.76 maximum or 0.05 minimum. Step 8. The solution from Step 7 is gradually incorporated into the mixture from Step 3. While mixing in a range not less than 190 rpm Step 9: To the mixture from Step 8 add 20g of trehalose, while mixing in a range of no more than 1-90 rpm for a period of not less than 10 minutes. Step 10: 0.35g of TRITON X-100 surfactant, available from Boehringer Mannheim Biochemists, is added to the Step 9, while mixing a range of no more than 190 r.p.m.

This mixture should continue mixing for no less than 5 minutes. Step 11: The enzyme solution from Step 6 is added to the mixture from Step 10 the reagent, now complete; it is mixed in a range of not less than 190. r-p.m. for a period of time of not less than 30 minutes.

Step 12: The reagent can now be filtered, as needed by the manufacturing team, by passing it through a 100 micron cribose bag or through a 100 micron integral filt through a pumping system. The glucose dehydrogenase quinoprotein apoenzyme specified above is obtained from Boehringer Mannheim GmbH Germany (Boehringer Mannheim identification number Gm 1464221). Alternatively, this apoenzyme can be obtained from the Acinetobacteria Calcoaceticus by the following protocol narrated in Duine et al., Letters FEBS, vol. 108, no. 2, p 443-46. Acinetobacteria Calcoaceticus grow in a salt miner supplemented with 0.02 molar (M) of sodium succinate 0.10M ethanol at 22 ° C with good aeration. These cells are harvested at the end of a logarithmic phase and a wet cell produced of ~ 4g / I can be obtained. The frozen cells (lOg) are thawed and mixed with 15 millimeters (ml) of 36 ilimolar (mM) Tris / 39 mM glycine buffer. After adding 6 milligrams (m isozyme), the suspension is mixed at room temperature for 15 minutes and centrifuged for 10 minutes at 48,000 X. Floating is discarded and the pill extracted twice with 36 Tris / 39 mM glycine buffer, containing 1% TRITON 100 surfactant is present in the extract, the enzyme is extracted with 0.1M potassium phosphate (pH 7.0) The enzyme is then dialyzed against 0.1M sodium acetate (pH 4.5), which contains 3M bromide of potassium at 4 ° C for 72 hours.The enzyme is then dialysed against 0.02M potassium phosphate (pH 7.0) for 12 hours, resulting in the apoenzyme.In the presented test strip, the opening Ll is around 3.2 millimeters up to about 6.7 millimeters In the presented modality of a glucose test strip, 4.5 microliters of test reagent made with the above protocol are added to the aperture 1_1 (see Fig. 3f). superf exposed conductive surfaces of tracks 5 and 6 in opening _1_1. The test reagent 1_2 is then dried at about 70 ° C for about 1 to 2 minutes. The prespressed result, a dry glucose reagent film, will contain about 2000 to about? 9000 units of enzyme activity per gram of reagent. The reagent presented will contain the following additional components per gram of reagent: 62.2 milligrams (mg) of polyethylene oxide 3.3 mg of NATROSOL 250M 41.5 mg of AVICEL RC-591 F 89.4 g of potassium phosphate monobasic 157.9 mg of potassium phosphate dibasic 437.3 mg potassium ferricyanide 46.0 mg sodium succinate 148.0 mg trehalose 2.6 mg TRITON X-100 surfactant It is importantly included in about 0.2% by weight to about 2% by weight of polyethylene oxide having a medium weight molecular weight of around 10 kilodaltsns up to 900 kilodaltons, and preferably around 0.71% by weight of polyethylene oxide having a molecular weight average of 300 kilodaltons, in the wet reagent referred to above provides a test reagent which, when dry, is more firm for the steps of the strip process such as a mechanical perforation, firmer to the mechanical manipulation by the user of the test strip, and which network isolve or resuspend an aqueous sample, such as human blood when added. After drying the percentage of polyethylene oxide fluctuates from about 1.75% (heavy weight) to around 17.5% (heavy weight). In the dry reactant presented, the percentage of polyethylene oxide is around 6.2 (weight). The preferred thickness of the dry glycogen reagent film, it will be such that in combination with the inherent properties of the test chemistry, the test sensitivity to the interference by the mitigated hematocrit variation. In this preferred embodiment of the invention, the thickness of the film (as calibrated by the ratio of the wet reactive volume distributed to the surface area exposed by opening XX) is such that 4.5 microliters of reagents are distributed within an area of approximately 22 square millimeters ( the preferred area of the opening ü). includes polyethylene oxide from about 100 kilodalt to about 900 kilodaltons of molecular weight in a film with the thickness described above, results in a sensor that processes a reduced sensitivity to hematocrit variation when glucose is measured from a sample of human blood . After the test reagent 12 is dried in opening XX, the cover 13 is supported on the opening H fixedly adhesive to the surface 8. as described above. The cover 12 is made by itself in a separate process according to the procedures described below. Preferably, the cover 13 is made of a MELINEX 561 polyester flake, having a thickness of 5 mil. A substantially opaque ink is printed on the first surface 16 in the pattern 27 such that the window 18 remains transparent or translucent. The window is positioned and dimensioned so that when the cover is fixed to the surface 8, it will align with the opening H as shown in Fig. 3h. On the second surface 12 / a laminated adhesive system so that the cover can finally be fixed to surface 8. This adhesive system can be conveniently an acrylic adhesive such as that available from many commercial sources, but preferably from 3M Inc., In short, before placing the cover on the surface 8 a piece of transparent or translucent plastic coated preferably a polyethylene teretalate (PET), such as Melinex S plastic from about 0.001 to about 0.004 inches thick, is located against the adhesive system on the second surface 17, and aligned with and, extending beyond the dimensions of the window JJ. This coated plasti is the hydrophilic coating 25. The coating 25 is specifically chosen to provide a hydrophilic nature to the inner surface of the capillary test chamber to favor the fluid of an aqueous sample, such as blood, within the test chamber. The coating can be chosen from many coatings available to exhibit a hydrophilic surface, but product number ARCARE 8586, available from Adhesiv Research, Inc., is preferred. The coating 25 also acts to prevent direct contact of the adhesive reagent of the cover 12. Finally the cover 13 is placed on the surface (see Fig. 3h). It is at this level that the transparent or translucent window 18 defined by the absence of ink printed on the cover 13 should be aligned with the opening H as shown in Fig. 3h. The dimensions of the transparent translucent window 18 should be chosen such that a substantial fraction of the width (greater than, about 75%) of the capillary channel lying beneath, is visible through the window 18 The orthogonal dimension of the window 18 should exposing the entire width of the electrode in operation 5. Therefore with a sample, such as blood, is introduced into the capillary test chamber, through the application port of sample 2fi, it is possible for a user of reasonable visual acuity determine if the window is completely full of sample. To choose the dimensions of the window as it was proposed, it is possible to provide feedback for the user of the test run, that the strip has been sufficiently dosed with a test sample. The visual confirmation of the full window provides the guarantee that a sufficient area of electrode in operation will be covered with the sample and that a sufficient part of the counter or reference electrode 6 is covered as well. This coverage of the electrodes by the test sample is important to carry out a safe test on a capillary filled electrochemical biosensor This visual confirmation of the sufficient dosage of the test strip, provides a safeguard against erroneous test results due to low dosing not detected d the test strip. The completed test strips 26 are used in conjunction with a meter capable of measuring some electrical properties of the test sample after the addition of the test sample to the test application port 2_Q (see Fig. 2). The electrical property that is measured can be, for example, electric current, electric potential, electric charge, impedance. An example of measuring changes in electrical power to perform an analytical test is illustrated by the U.S. patent. No. 5,413,690, the statement of which is by this means incorporated by reference. An example of an electric current measurement for performing an analytical test is illustrated by the U.S. patent. Nos. 5,288,636 and 5,508,171, the declarations of which are hereby incorporated by reference. In the preferred embodiment, test strip 2 is connected to a meter, which includes a power source (a battery). Improvements in such meters and a biosensor system can be found in the U.S. patents. Nos. 4,999,632; 5,243,516; ,366,609; 5,352,351; 5,405,511; and 5,438,271, the declarations of which are hereby incorporated by reference.

Many analyzes containing fluids can be analyzed by the electrochemical test strip of the present invention. For example, analysis in fluids of the human body, such as whole blood, blood serum, urine and cerebrospinal fluid can be measured. Also, analyzes found in fermentation product and in environmental substances, which potentially contain environmental contaminants, can be measured. To determine the concentration of glucose in a human blood sample with the preferred test strip stated above, in which lanes 5 and 6 are palladium of substantially the same size and the glucose reagent in the reagent as specified above, a sample can be added to the sampling application port Zü - The sample will be deposited inside the test chamber by capillary action. Once inside the test chamber, the blood sample will be mixed with the test reagent 12 / after an incubation period for some desired time, for example 3 seconds, a potential difference will be applied by the power source of the meter between the tracks ¿and 6. In the preferred mode, the applied potential difference is d 300 millivolts. The current can be measured at any time from 0.5 seconds to about 30 seconds after the potential difference of 300 millivolts is applied. The measured current may be correlated to the glucose concentration in the blood sample. The current measured during the test of an analysis of a fluid sample can be correlated to the concentration of the analysis in the sample by the application of an algorithm by the current meter. The algorithm can be a simple one, as illustrated in the following example: [substance being analyzed] = Ci7.5 + d In which [substance being analyzed] represents the concentration of the substance that is analyzed in the sample (see Fig. 6), I7.5 is the current (in microamperes) measured in 7.5 seconds after the application of the applied potential difference between the electrodes, C is the slope of the line 3_0 (Fig. 6), and d is the intercepted axis (Fig. 6). By making measurements with known concentrations of the substance being analyzed, the calibration curve _30 (Fig. 6) can be constructed. This calibration will be recorded in the switch of the Read Only Memory (ROM) meter and will be applicable for a particular batch of test strips. Lines 3JL and 3_2 in Fig. 6 represent other hypothetical calibration curves for two batches of test strips. The calibration for these batches of biosensors would carelessly generate different values for C and d in the previous algorithm. In a preferred method for the analysis of glucose from a whole human blood sample, the current measurements are made in 0.5 second intervals, from 3 to 9 seconds after the potential difference is applied between the electrodes. These current measurements correlate the concentration of glucose in the blood sample. In this example of glucose measurement of a sample of blood, the measurements of currents are made at different times (from 3 seconds to 9 seconds after the application of the potential difference), on the contrary d a fixed time (as shown in FIG. described above), and the resulting algorithm is more complex and can be represented by the following equation: where ia. is the current measured in the first measured time d (3 seconds after the application of the potential difference of 300 millivolts), i2 is the current measured in the second measurement time (3.5 seconds after the application of the potential difference) of 300 millivolts), i3 is the current measured in the third measurement time (4 seconds after the application of the potential difference of 30 millivolts), U is the current measured at the measured time (in this example, at the 13th measurement time or 9 seconds after the application of the potential difference of 3 millivolts), L, C2, C3 / and Cn they are coefficients derived from a multivariate analytical regression technique, such as the Principle of Analysis of the Components or the Partial Minimum Squares, and d is the interception of regressions (units of concentration in glucose). Alternatively, the glucose concentration in the sample being measured can be determined by integrating the curve generated by the tracer current, i, against the measurement time over the time interval (for example, from 3 seconds to seconds after the application of the difference of power of 300 millivolts), obtaining in this way the tot charge transferred during the measurement period. The load transferred is directly proportional to the glucose concentration in the sample being measured. Additionally, the measurement of the concentration of glucos can be corrected by the differences between the environmental temperature in the time of the current measurement and the ambient temperature in the time that the calibration was performed. For example, if the calibration curves for the measurement of glucose were constructed at room temperature of 23 ° C, the glucose measurement is corrected using the following equation: [Glucose jCCTrβ «1? = [Glucose] macaí? X (lK (T -23 ° C)), where T is the ambient temperature (in ° C) at the sample measurement time and K is a constant derived from the following regression equation: Y = K (T-23), In which [Glucose] ms jda a.23 [Glucose] mprprv »a T c: y = to calculate the value of K, each of the multiple glucose concentrations is measured by the meter at various temperatures, T, and 23 ° C (the basic case). Then, a linear regression of Y on T-23 is performed. The value of K e a residue of this regression. Various features of the present invention can be incorporated into other electrochemical test strips, such as those disclosed in U.S. Patent Nos. 5,120,420; 5,141,868; 5,437,999; 5,192,415; 5,264,103; 5,575,895, the statements of which are hereby incorporated by reference. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property.

Claims (1)

1. CLAIMS A test strip, having a slit along one edge for tactile identification of the test application port, said test strip is characterized in that it comprises: a first insulating substrate having first and second surfaces, a slit at length of a shore and a vent; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces, a slit along one edge, first and second openings, the second surface is fixed to the conductive tracks and to the first surface of the first insulating substrate, the first opening exposing a portion of the conductive tracks for electrical connection to a meter capable of measuring an electrical property, the second opening is located along said edge and exposes a different portion of the conductive tracks and the vent; a test reagent covering at least a portion of the conductive tracks exposed by the second opening; and a cover having first and second surfaces and a slit along one edge, the second surface of the cover is fixed to the first surface of the second insulating substrate and positioned such that the second surface of the cover and surface of the first insulating substrate form opposite walls of a capillary chamber filled with a sample application port on said edge of the second insulator, in which the second opening in the second insulating substrate and the grooves in the first substrate, the second substrate insulation, and the cover are aligned to provide of. such a tactile identification of the port of application of the sample. a test strip, characterized in that it comprises: a first insulating substrate having first and second surfaces, a notch along a shore and a vent; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces and first and second openings, the second surface is fixed to the conductive tracks and to the first surface of the first insulating substrate, first opening exposing a portion of the conductive pistons for electrical connection to a median capable of measuring an electrical property, the second opening is located along a shore of the second insulating substrate and exposes a different portion of the conductive tracks, the notch in the first insulating substrate, and the vent; a test reagent that covers at least a portion of the conductive tracks exposed by the second opening; and a cover having first and second surfaces and a notch along one edge, the second surface of the cover is fixed to the first surface of second insulating substrate and positioned such that the second surface of the cover and the first surface of the first substrate forms opposite walls of a full capillary chamber, and 2) the notch in the cover covers the notch in the first insulating substrat, by means of which the notch in the cover and the sample in the first insulating substrate will cause a sample watery liquid, when touched by the port. d sample application, to flow into the capillary chamber without significant hesitation. a test strip, characterized in that it comprises: a first insulating substrate having first and second surfaces and a vent; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces and first and second openings, the second surface is fixed to the conducting tracks and to the first surface of the first insulating substrate, the first opening exposing a portion of the electrically conductive tracks for electrical connection with a meter capable of measuring an electrical property, the second opening is located along one edge of the second insulating substrate and exposes a different portion of the conductive tracks and the vent; a test reagent covering at least a portion of the conductive tracks exposed by the second opening; and a cover having first and second surfaces and a transparent or translucent solid window, the second surface of the cover is fixed to the first surface of the second insulating substrate and positioned such that it covers the second surface of the second insulating substrate and so such that the second surface of the cover the first surface of the first insulating substrate form opposite walls of a capillary chamber filled with a sample application port on said edge of the second insulating substrate, and the transparent or translucent window is dimensioned and positioned so such that the window extends from the sample application port, and covers the entire width of one of the electrically conductive tracks and at least about ten percent of the width of the other electrically conductive track. A reagent for a test strip, characterized in that it comprises: the appropriate reaction components to perform a test, and a non-washable or suspendable film forming a mixture that includes from about 0.2% by weight to about 2% by weight of the oxide polyethylene having a molecular weight of about 100 kilodaltons up to about 900 kilodaltons, in which the reagent can be applied to the test strip in a wet form, can subsequently be dried, and then redissolved or resuspended on the sum of an aqueous test sample to the dry reagent. The test strip of claim 1, further characterized in that it comprises: a first groove along the groove in the first insulating substrate, and a groove along the groove in the cover, both, the first and second grooves are located in such a way that they cover each other. The test strip of claim 1, characterized in that the cover has a transparent and translucent solid window, which is sized and located in such a mucus that the window covers the entire width of the electrically conductive track that is closest to the slit. of the first insulating substrate and at least about ten percent of the width of the other electrically conductive track. The test strip of claim 5, characterized in that the cover has a translucent transparent solid window, which is dimensioned and positioned such that the window covers the entire width of the electrically conductive piston that is closest to the slit of the first substrate. insulating and at least about ten percent the width of the other electrically conductive piston. The test strip of claim 1, characterized in that the test reagent includes the appropriate reaction components to perform a test, and a washable or suspendable film forming the mixture including from about 0.2% by weight to about 2% by weight of polyethylene oxide having a molecular weight of about 100 kilodaltons up to about 900 kilodaltons, in which the test reagent can be applied to the test strip in a wet form, can be subsequently dried, and then redissolved or resuspended on the sum of an aqueous test sample to dry reagent. 9. The test strip of claim 5, characterized in that the test reagent includes the appropriate reaction components to perform a test, and a washable or suspendable film forming the mixture including from about 0.2% by weight to about 2% Weight of polyethylene oxide having a molecular weight of from about 100 kilodaltons to about 900 kilodaltons, in which the test reagent can be applied to the test strip in a wet form, can be dried subsequently, and then redissolved or resuspended on the sum of an aqueous test sample to dry reagent. 10. a test strip of claim 6, characterized in that the test reagent includes the appropriate reaction components to perform a test, and a non-washable or suspendable film forming the mixture including from about 0.2% by weight to about 2% of polyethylene oxide weight that has a molecular weight of about 100 kilodaltons up to about 900 kilodaltons! in which the test reagent can be applied to the test strip in a wet form, it can be subsequently dried, and then redissolved or resuspended upon the sum of an aqueous test sample to dry reagent. 11. The test strip of claim 7, characterized in that the test reagent includes the appropriate reaction components to perform a test, and a washable or suspendable film forming the mixture including from about 0.2% by weight to about 2% Weight of polyethylene oxide having a molecular weight of from about 100 kilodaltons to about 900 kilodaltons, in which the test reagent can be applied to the test strip in a wet form, can be dried subsequently, and then redissolved or resuspended on the sum of an aqueous test sample to dry reagent. 12. The test strip of claim 1, characterized in that the second surface of the cover includes a hydrophilic coating. 13. The test strip of claim 5, characterized in that the second surface of the cover includes hydrophilic coating. 14. The test strip of claim 6, characterized in that the second surface of the cover includes hydrophilic coating. 15. The test strip of claim 7, characterized in that the second surface of the cover includes a hydrophilic coating. 16. The test strip of claim 8, characterized in that the second surface of the cover includes hydrophilic coating. 17. The test strip of claim 9, characterized in that the second surface of the cover includes hydrophilic coating. 18. The test strip of claim 10, characterized in that the second surface of the cover includes hydrophilic coating. The test strip of claim 115, characterized in that the second surface of the cover includes a hydrophilic coating. The test strip of claim 7, wherein the test reagent includes the appropriate reaction components for the test, and a non-washable or suspendable film forming the mixture that includes from about 0.2% by weight to about 2%. of the weight of polyethylene oxide having a molecular weight weight of 300 kilodaltons. The test strip of claim 20, characterized in that the polyethylene oxide is about 0.71% by weight. A reagent for a test strip, characterized in that: the reaction components are suitable for performing a test and from about 1.75% by weight to about 17.5% by weight of polyethylene oxide having a weight of molecular means from about 100 kilodaltons up to about 900 kilodaltons, The test strip of claim 1, characterized in that the test reagent includes: the appropriate reaction components to perform a test and from about 1.75% by weight to about 17.5% by weight of oxide of polyethylene which has a weight of molecular medium from about 10 kilodaltons to about 900 kilodaltons, in which the reagent will be redissolved or resuspended on the sum of an aqueous test sample for the reactive. The test strip of claim 5, characterized in that the test reagent includes: the appropriate reaction components to perform a test and from about 1.75% by weight to about 17.5% by weight of polyethylene oxide having a weight of molecular medium from about 10 kilodaltons to about 900 kilodaltons, in which the reagent will be redissolved or resuspended on the sum of an aqueous test sample for the reactive. The test strip of claim 6, characterized in that the test reagent includes: the appropriate reaction components to perform a test and from about 1.75% by weight to about 17.5% by weight of polyethylene oxide having a weight of molecular medium from about 10 kilodaltons to about 900 kilodaltons, in which the reagent will be redissolved or resuspended on the sum of an aqueous test sample for the reactive. The test strip of claim 7, characterized in that the test reagent includes: the appropriate reaction components to perform a test and from about 1.75% by weight to about 17.5% by weight of polyethylene oxide which has a weight of molecular medium from about 10 kilodaltons to about 900 kilodaltons, in which the reagent will be redissolved or resuspended on the sum of an aqueous test sample for the reactive. 27. The test strip of claim 26, characterized in that the molecular weight of the polyethylene oxide is 300 kilodaltons. 28. The test strip of claim 27, characterized in that the increase in polyethylene oxide in the reagent is about 6.2% by weight. 29. A method for selectively increasing the hydrophilicity of a surface by the corona treatment, characterized in that r a corona arc is applied to the surface at a density of Watt from around 20 to around 90 Watts per centimeter per second; then a film of water is selectively applied in the area in which it is desired to reverse the corona treatment effect; and then the water is removed by drying, 30. The method of claim 29, characterized in that the water film is applied in a thickness of about 1.5 microns to about 3.0 microns. 31. The method of claim 30, characterized in that the water is deionized water. 32. The method of claim 31, characterized in that the corona arc is applied at a distance of about 0.040 inches from the surface. 33. A test strip, having a slit along a shore for tactile identification of a sample application port, said test strip characterized in that it comprises: a first insulating substrate having first and second surfaces and a slit throughout from a shore; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces, a slit along one edge and an opening, the second surface is fixed to the conductor tracks and to the first surface of the first insulating substrate, the second insulating substrate is configured to expose a portion of the conductive tracks for electrical connection to a meter capable of measuring an electrical property, the opening is located along said edge, and exposes a different portion of the conductor tracks; a test reagent covering at least a portion of the conductive tracks exposed by the opening; a cover having first and second surfaces and a slit along one edge, the second surface of the cover is fixed to the first surface of the second insulating substrate and is positioned to cover the opening and so that the second surface of the cover and the first surface of the first insulating substrate form opposite walls of a full capillary chamber, with a sample application port on said edge of the second insulating substrate; and a vent that communicates with the full capillary chamber; wherein the opening in the second insulating substrate and the slits in the first insulating substrate, the second insulating substrate, and the cover, are aligned to provide thereby a tactile identification of the test application port. A test strip characterized in that it comprises: a first insulating substrate having first and second surfaces and a notch along one edge; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces and an opening, the second surface is fixed to the conductive tracks and to the first surface of the first insulating substrate, the second insulating substrate is configured to expose a portion of the conductor tracks. for the electrical connection to a meter to measure an electrical property, the opening is located along one edge of the second insulating substrate and exposes a different portion of the conductor tracks, and covers the notch in the first insulating substrate; a test reagent for at least a portion of the conductive tracks exposed by the opening; a cover having first and second surfaces and a notch along one edge, the second surface of the cover is fixed to the first surface of the second insulating substrate or positioned in such a way that 1) the second surface of the cover and the first surface of the first insulating substrate form opposite walls of a capillary chamber filled with a sample application port on said edge of the second insulating substrate, and 2) the notch in the cover covers the notch in the first insulating substrate; and a vent communicates with the full capillary chamber; in which the notch in the cover and the notch in the first insulating substrate will cause an aqueous liquid sample, when it touches the test application port, to flow into the capillary chamber without significant hesitation. A test strip characterized in that: a first insulating substrate having first and second surfaces; at least two electrically conductive tracks fixed to the first surface of the first insulating substrate; a second insulating substrate having first and second surfaces and an opening, the second surface being fixed "to the conductive tracks and to the first surface of the first insulating substrate, the second insulating substrate is configured to expose a portion of the conducting tracks for the connection electrical to a meter layers measuring an electrical property, the opening is located along one edge of a test reagent covering at least a portion of the conductive tracks exposed by the opening, a cover having first and second surfaces and a transparent and translucent solid window, the second surface of the cover is fixed to the first surface of the second insulating substrate and placed such that it covers the second insulating substrate and d such that the second surface of the cover and the first surface of the first Insulating substrate forms opposite walls of a capillary chamber filled with a port of application of shows on said edge of the second insulating substrate, and the transparent translucent window which is dimensioned and positioned so that the window extends from the sample application port, and covers the entire width of one of the electrically conductive tracks and thus less around d ten percent of the width of the other electrically conductive piston; and a vent that communicates with the full capillary chamber. The test strip of claim 33 further characterized in that a first notch along the slit of the first insulating substrate, and a notch along the notch of the cover, both, the first second notches, are located in such a way that Cover each other. The test strip of claim 33, characterized in that the cover has a translucent transparent solid window, which is dimensioned and positioned such that the window covers the entire width of the electrically conductive piston that is closest to the slit of the first substrate. insulating and at least about ten percent the width of another electrically conductive piston. The test strip of claim 36 characterized in that the cover has a translucent transparent solid window, which is dimensioned and positioned so that the window covers the entire width of the electrically conductive piston that is closest to the slit of the first insulating substrate. and at least about ten percent of the width of the other electrically conductive piston. TEST STRAND BIOSENSOR ELECTROCHEMICAL IMPROVED SUMMARY The biosensor includes a first insulating substrate (1), with a first surface (22) and a second surface (23). The substrate (1) additionally includes the slit (2), the notch (3) and the vent (4).